Method of and apparatus for converting electric currents



2 Sheets-Sheet 1,

(No Model.)

B. THOMSON. METHOD OF AND APPARATUS FOR CONVERTING ELEGTRIG OURRENTS.

No. 595,419. Patented Dec. 14,1897.

Tl'l/ Qrnisas- Q l 2 Sheets-Sheet 2.

(No Model.)

B. THOMSON. METHOD OF AND APPARATUS FOR CONVERTING ELECTRIC GUR BNTS.

Patented Dec. 14,1897.

VII/ 71%" r ya YHE Noam PEYERS (.04 PHO'TO-UTHO, \MaHNGTON, o c,

UNITED STATES PATENT QFFICE.

ELIHU THOMSON, OF SVVAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO THE GENERALELECTRIC COMPANY, OF NEIV YORK.

METHOD OF AND APPARATUS FOR CONVERTING ELECTRIC CURRENTS.

SPECIFICATION forming part of Letters Patent No. 595,419, dated December14, 1897.

Application filed February 27, 1897. Serial No. 626,313. (No model.)

T 0 It 1077,0772, it nea /0072 0017? Be it known that 1, ELIHU THOMSON,a citizen of the United States, residing at Swampscott, in the county ofEssex, State of Massachusetts, have invented certain new and use fulImprovements in Methods of and Apparatus for Converting ElectricCurrents, (Case No. 512,) of which the following is a specification.

My present invention relates to the workin g of high-potential apparatusfrom such circuits as those used for continuous-current lighting orcircuits which have a definite direction of current at constantpotential.

My invention consists, broadly, in energizing a magnetizable core by acoil acting as a primary fed from the mains, inductively substitutingfor this coil at the moment of rupture of its circuit a second primary(which may be called a secondary primary) of low potential, accumulatingby induction in the second primary on closed circuit a vigorous chargeand at the proper interval breaking the secondary primary with orwithout a condenser across the point of rupture, whereby the secondaryprimary becomes virtually a low-potential primary traversed by a heavycurrent which is suddenly interrupted, and the interruption of whichreacts vigorously upon the other windings around the core to set up inthem high potentials.

In the accompanying drawings, Figure l is a diagrammatic view of anarrangement,showing the coil in section and the connections to thedifferent commutating devices. Fig. 2 is a diagram of circuitconnections embracing a modified form of Fig. 1. Fig. 3 is a View of asuitable commutator. Figs. at and 5 are further modifications. Fig. 6 isan arrangement by which all of the fine winding may be used to furnishthe inductive discharge. Fig. 7 is a view of an insulating device forthe commutator, and Figs. 8 and 9 are diagrams of circuit connections.

In Fig. 1, 'm 72. represent the terminals of the line, which may beassumed to be of one hundred to two hundred volts potential. A branchtaken from this line feeds the primary P around the core 0, in which maybe used, if desired, a regulating-resistance R. The primary P has aconsiderable number of turns and is of comparatively small wire, theobject being to charge the core C magnetically within an interval oftime more or less great. If it is to be done in a short time, thewinding P is made coarse, but if in a longer time the winding P shouldbe finer. The circuit of the winding P is closed at intervals by acommutator G, upon which rests a brush B. On the rupture of the circuit,when the segment G in revolving leaves brush B, the brush touches thefollowing segment f, insulated from the first and connected to oneterminal of the condenser F,the other terminal of which is connected toa line a, leading to segment G. On the same shaft with segment G andelectrically connected with it is mounted a second segment G Thissegment G is followed by the condenser-segment f, and brush B slides onthese segments successively. B makes contact with segment G at or aboutthe time that segment G breaks contact with brush B. Brush B is oneterminal of a heavy coil P ,wound upon the core C, in close inductiverelation to coil P. It may be called the secondary primary coil. Outsideof these coils is the ordinary secondary winding .9 s of aninduction-coil, the terminals 25 i being separated. A spark D is shownbetween them. The return connection from the coil P to the line m isindicated at Z).

The operation of the device is as follows: The closure of contact ofsegment G with brush B permits current to pass through a circuit from m,through connection I), through coil P to brush B, to segment G, toconnection a, to resistance R, to line it. The current during therevolution of segment G begins at a low value, being opposed byinductance of coil P, and gradually rises to its maximum. At this momentit is broken by the revolution of the segment G, which leaves B. As thesegment G leaves the brush B segment f is substituted. The condenser Fis thus thrown across the break. Meanwhile, however, at the moment ofbreaking contact between G and B segment G comes into contact with brushB closing the circuit of the secondary primary P for a short interval,during which there is induced by the rupture of the primary P a heavycurrent in the coil P representing in fact almost the entire en ergy ofthe circuit P, transferred to P in stantaneously as a substitutecircuit. As soon as this current has reached its full value it is brokenby the rupture of G with brush B and the condenser is again, by segmentf, thrown across the break of the secondary primary circuit. Theimmediate effect is the collapse of the magnetism of the core C and theproduction of an intense inductive effect in all the windings. One ofthese is the work circuit S S, the normal secondary of theinduction-coil, in which it manifests itself by a great rise ofpotential at the terminals, and if these are not too distant a spark isproduced, or if vacuum-tubes be used an illumination and discharge fromthe secondary circuit occurs. lVhile this action is occurring and rapidmakes and breaks take place at the break-piece, there is only a slightspark produced there, because the rupture of the high-potential primary,which would ordinarily be attended by a flaming and spark, is made at orabout the time when the secondary primary P is a closed circuit. Thisaction kills the inductance of P (upon which its sparking depends) andallows the current to be suddenly cutoff in it. lVhatever slight sparkmight be produced is taken care of by the condenser F. Some inductanceof course remains, owing to the fact that the coil P cannot be socompletely intermingled with the coil P as to practically occupy thesame space.

Fig. 2 shows in a diagrammatic way the same elements as before, butshows also that the coil P, which is the first primary, may also act aspart of the coil 8 s of Fig. 1 and become the discharging secondary.This is particularly the case when the potentials be tween m and n areconsiderable, as when it is two hundred and twenty or five hundredvolts. In this case the turns of the coil P may be very many. sizedapparatus they maybe ten thousand to twenty thousand turns, the turns atP being made, as before, very few and relatively coarse. The action onthe closure of circuit P is to pass an increasing current up to fullvalue from the mains m n, which is cut off by segment G leaving thebrush B. At the same moment the circuit of coil P is closed, and theenergy is transferred immediately thereto. This is afterward followed bythe rupture of the coil P and its reaction on the fine-wire coil P, withthe consequent production of high potentials at the terminals '6 t. Inthis case it is desirable that the break-piece be well insulated and atleast the brush B and segment G operated in oil or other insulatingfluid. lVhere, however, the potentials developed are not sufficient torequire this precaution, the break-piece may take the form shown in Fig.3, where the segment G is prolonged to the left to form the tongue Gupon which the brush B bears, while B bears upon G, as before. Thecondenser-segment f has a strip which is common to both brushes B and BFor example, for a moderate and immediately follows the segment G. Thesegment G is connected by a brush 11 to the other parts of the circuit.This brush rests on a ring 7L2, while on the other side is a brush H,having a similar office for the condensersegment f. All the parts of theapparatus otherwise are thoroughly insulated.

Fig. 4: shows that if the potential of the coil P be made low enoughthatis, if its winding be made of very few turns-then the condenser might bedispensed with, provided the potential set up on the rupture of thecircuit P is so low as not to involve destructive spark. In this caseall that is necessary is to provide for a good closure of the terminalsof l? by a contact-maker G which follows immediately upon the rupture bybrush B from segment G, in circuit with the coil P, this action againbeing followed by rupture of circuit l. soon after.

Fig. 5 shows a form of my invention in which the coil P is energized, asbefore, from connections to the mains in it, taken from the line throughbrush B, segment G, and brush H and having a condenser F andcondensersegment f, related as before. The circuit of coil l -tl1at is,the substitute circuit-is in this case not closed m etallically, butthrough a condenser F of limited capacity by brushes B B resting upon acontact device G the connection of which follows the contact-breaking inthe circuit of P either immediately or at about the same time. In thiscase the coil P may be made of fine wire of many turns, and thecondenser F furnishes for it a circuit virtually closed, but foralimited time. The discharge of the coil P finds a substitute path orsubstitute circuit for the energy in P- that is, on the rupture of thecircuit P" by the brush B and segment G, the circuit of P having beenclosed, current flows in it, which charges the condenser F which permitsthe rupture of the first circuit P substantially without spark. As thecondenser F has but limited capacity, the circuit P is virtually broken,or at least the current therein is stopped and suddenly reversed, by thedischarge of the condenser, thus giving the effect of an actual break,which may be utilized as is the break in the former figures.

Fig. 6 shows another form of myinventiou. The iron core C, consisting ofa bundle of iron wires in the usual form, is wound around with a fewturns of heavy conductor, forming the coil P lVell insulated from thisis a coil of fine wire, the inner layers of which constitute the coil P,corresponding to the coil P of Fig. 1, while the outer turns, which maybe of relatively smaller gage, are simply a continuation of the coil P,the terminal of this outer winding being at i while the other terminalof the outer winding is the same as that connected to the main circuitm. In this way all of the finer winding around the core is effective asa source of electromotive force in maintaining the discharge between theterminals t i while a portion of the finer windpotential closed circuit.

ing (of proper gage to convey the current) is used as theenergizing-circuit. The coarse layer or winding is the substituteprimary or the secondary primary. The whole structure may be immersed ina box of oil, as indicated by the dotted lines. If now current be passedin at m, it will traverse, say, eight or ten layers of the outer finewindingthat is, in the section P and reach-brush Band if segment G be incontact with the brush it will pass to segment G, thence back toconnection n. During the period of contact the current will increase andhighly magnetize the core 0. hen segment G breaks with brush B,condenser-segment f touches brush B, and the break is thus made with thecondenser F across the gap; but this alone would not suffice to preventdamaging sparking, and therefore at or near the moment of breaking acircuit is completed by segment G through brush B and coil I as a shortcircuit of low potential, thus instantaneously transferring the energyfrom coil P to thelow- This transfer prevents sparking on the breakingof brush B with segment G. The brush B then leaves segment G andruptures the coarse-wire circuit, while condenser-segmentfacts toconnect condenser F across the new break thus formed. At this moment,however, the brush B has reached the position shown in the figurebetween the condenser-segment f and segment G, being completelyinsulated. This is necessary on account of the high potentials developedin the circuit P, of which it is one terminal. The result of the suddenrupture of the curcuit P with condenser F across the break is to inducea vigorous high-potential charge in all of the fine wire from terminal25 to terminal 25, and according to the number of turns the length ofspark produced may be determined. I have in this way, with cores of ironwire of about twelve inches long and one and one-half inches indiameter, obtained an induction of about three volts perturn, which withten thousand turns would give thirty thousand volts. In such a case theturns impressed at m n by a potential of one hundred and ten volts-thatis, the turns i11- cluded in the section P P-may equal thirty thousand.A coil in which the fine wire is twenty thousand turns may easily yieldiiveinch sparks between the terminals when operated according to myinvention, the actual energy consumed from the circuit m 'n, being -veryslight, showing that the apparatus is tact breakingandmakingdevices.Thesame effect is obtained, however, by enlarging the diameter of thebreak-piece upon which 13 is used. This may readily be done, because thecurrent which passes the brush B is comparatively very small.

Figs. 8 and 9 show in diagram ways of connecting up the different partswhen the arrangement is like that in Fig. 6. In Fig. 8 the line M goesto one end of the coil P, the circuit being completed through thebreakpieces and brush B, as in Fig. 6, the spark ing terminals includingthe entire finer winding of the coil, as in that figure. The coil P isalso connected as in Fig. 6 and the condenser F is shown as in circuitaround the coil P. Fig. 9 shows the same connections practically as inFig. 8, the connection of the main m to the coil P being at the otherend of that coil or to its junction with the finer winding included inthe sparking circuit. Otherwise the connections in Fig. 9 are the sameas those in Fig. 8 or in Fig. 6.

It is to be understood that various modifications of the arrangementsmay be made involving the same principles of operation. For example,properly-arranged vibrating break-pieces might be employed instead ofrotating devices. In the same way, while a single core is shown, theseparts may be changed or duplicated in the same system and will operateby sets of break-pieces or by a single break-piece in accordance with myinvention; but these are obvious substitutions of equivalents. Thedischarges furnished by the apparatus of my invention may be employed towork vacuum-tubes, to produce ozone, or, in general, for any purpose towhich such currents are applicable.

The foundation upon which my invention chiefly rests is the substitutionof a well-closed secondary in intimate inductive relation with theenergizing-primary energized at fairly high potential, such substitutionbeing made at or about the time of rupture of the first or energizingcircuit and such substitute coil having its circuit afterward brokenwhile the current is vigorous.

lVhat I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. The art of converting electric energy herein set out, which consistsin energizing a coil at relatively high potential, breaking the circuitof the coil and at about the same time closing the circuit of alow-potential coil in inductive relation thereto, and then interruptingthe current-flow in the second coil, thereby setting up in another coilthe desired electromotive forces.

2. The art of converting electric energy herein set out, which consistsin energizing by continuous current a coil at relatively high potential,breaking the circuit of the coil at the time of maximum current-flow, atabout the same time closing the circuit of another coil in inductiverelation thereto, and breaking the circuit of the sec-0nd coil when itat tains its maximum energy, thus setting up in another coil the desiredelectromotive forces.

3. An inductive device for converting electric energy, consisting of aprimary wound for relatively high potentials, a secondary of lowresistance, and another coil wound for high potentials, with means forsuitably interrupting in sequence the circuits of the first two coils.

4 An inductive device comprising a core, a primary coil wound formoderately high po tentials, a secondary coil of low resistance, and athird coil wound for high potentials, the primary coil and the thirdcoil being electrically connected so that the entire finer Winding ofthe coil is utilized to generate a high-potential charge.

5. In combination, mains carrying continuous current of relatively highpotential, an inductive device comprising a primary fed from the mains,a secondary in inductive relation to the primary, and a third coil ininductive relation to the other two, with means for interrupting theprimary circuit and closing the normally open secondary circuit at aboutthe same time.

6. In combination, mains carrying continuous current of relatively highpotential, an inductive device comprising a primary fed from the mains,a secondaryof low resistance and a third coil, the three coils ininductive relation on a common core, with means for breaking the primarycircuit and closing the normally open secondary circuit at about thesame time, and for subsequently opening the secondary circuit.

7. In combination, mains carrying continuous current of relatively highpotential, an inductive device comprising a primary fed from themains, asecondary of low resistance and a third coil, the three coils ininductive relation on a common core, with means for breaking the primarycircuit closing the normally open secondary circuit at about the sametime, subsequently opening the secondary circuit, and for connecting acondenser across the terminals of the primary and secondary circuits atdesired times.

8. An inductive device of the class described, comprising a core withthree substantially independent windings thereon, means for opening andclosing the circuits of two of the coils in succession, and means forthrowing a condenser across the terminals of each cell as it is opened.

In witness whereof I have hereunto set my hand this 23d day of February,1897.

ELIllU THOMSON. Witnesses:

JOHN W. GIBBONEY, ALFRED PAUL.

